A team of researchers from Duke University tested 14 different types of maks and identified which ones do the best job at stopping respiratory droplets from spreading.
They found that the best masks were the surgical N95 masks, which are professionally fitted and mostly used by healthcare workers. Three-layer surgical masks and cotton masks also did an acceptable job of catching the droplets.
They found that folded bandanas and knitted masks offered little to no protection.
The researchers were shocked to discover that some face coverings actually made the problem worse. Neck fleeces, which are used by runners, resulted in a higher number of droplets. The researchers found that the material broke down the larger droplets creating a high number of smaller droplets to form.
"We were extremely surprised to find that the number of particles measured with the fleece actually exceeded the number of particles measured without wearing any mask," Martin Fischer, one of the authors of the study, told CNN. "We want to emphasize that we really encourage people to wear masks, but we want them to wear masks that actually work."
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